Etched planarized VCSEL

ABSTRACT

An etched planarized VCSEL includes: an active region; a blocking region over the active region, and defining apertures therein; and conductive channel cores in the apertures, wherein the conductive channel cores and blocking region form an isolation region. A method of making the VCSEL includes: forming the active region; forming the blocking region over the active region; etching the apertures in the blocking region; and forming the conductive channel cores in the apertures of the blocking region. Another etched planarized VCSEL includes: an active region; a conductive region over the active region, and defining apertures therein; and blocking cores in the apertures, wherein the blocking cores and conductive region form an isolation region. A method of making the VCSEL includes: forming the active region; forming the conductive region over the active region; etching the apertures in the conductive region; and forming the blocking cores in the apertures of the conductive region.

CROSS-REFERENCE

This patent application claims priority to U.S. Provisional ApplicationNo. 62/372,126 filed Aug. 8, 2016, which provisional is incorporatedherein by specific reference in its entirety.

BACKGROUND

Lasers are commonly used in many modern communication components fordata transmission. One use that has become more common is the use oflasers in data networks. Lasers are used in many fiber opticcommunication systems to transmit digital data on a network. In oneexemplary configuration, a laser may be modulated by digital data toproduce an optical signal, including periods of light and dark outputthat represents a binary data stream. In actual practice, the lasersoutput a high optical output representing binary highs and a lower poweroptical output representing binary lows. To obtain quick reaction time,the laser is constantly on, but varies from a high optical output to alower optical output.

Optical networks have various advantages over other types of networks,such as copper wire based networks. For example, many existing copperwire networks operate at near maximum possible data transmission ratesand at near maximum possible distances for copper wire technology. Onthe other hand, many existing optical networks exceed, both in datatransmission rate and distance, the maximums that are possible forcopper wire networks. That is, optical networks are able to reliablytransmit data at higher rates over further distances than is possiblewith copper wire networks.

One type of laser that is used in optical data transmission is aVertical Cavity Surface Emitting Laser (VCSEL). A VCSEL has a lasercavity that is sandwiched between and defined by two mirror stacks. AVCSEL is typically constructed on a semiconductor wafer such as GalliumArsenide (GaAs). The VCSEL includes a bottom mirror constructed on thesemiconductor wafer. Typically, the bottom mirror includes a number ofalternating high and low index of refraction layers. As light passesfrom a layer of one index of refraction to another, a portion of thelight is reflected. By using a sufficient number of alternating layers,a high percentage of light can be reflected by the mirror.

An active region that includes a number of quantum wells is formed onthe bottom mirror. The active region forms a PN junction sandwichedbetween the bottom mirror and a top mirror, which are of oppositeconductivity type (e.g. one p-type mirror and one n-type mirror).Notably, the notion of top and bottom mirrors can be somewhat arbitrary.In some configurations, light could be extracted from the wafer side ofthe VCSEL, with the “top” mirror totally reflective—and thus opaque.However, for purposes of this invention, the “top” mirror refers to themirror from which light is to be extracted, regardless of how it isdisposed in the physical structure. Carriers in the form of holes andelectrons are injected into the quantum wells when the PN junction isforward biased by an electrical current. At a sufficiently high biascurrent the injected minority carriers form a population inversion inthe quantum wells that produces optical gain. Optical gain occurs whenphotons in the active region stimulate electrons to recombine with holesin the conduction band to the valance band which produces additionalphotons. When the optical gain exceeds the total loss in the twomirrors, laser oscillation occurs.

The active region may also include an oxide aperture formed using one ormore oxide layers formed in the top and/or bottom mirrors near theactive region. The oxide aperture serves both to form an optical cavityand to direct the bias current through the central region of the cavitythat is formed. Alternatively, other means, such as ion implantation,epitaxial regrowth after patterning, or other lithographic patterningmay be used to perform these functions.

A top mirror is formed on the active region. The top mirror is similarto the bottom mirror in that it generally comprises a number of layersthat alternate between a high index of refraction and a lower index ofrefraction. Generally, the top mirror has fewer mirror periods ofalternating high index and low index of refraction layers, to enhancelight emission from the top of the VCSEL.

Illustratively, the laser functions when a current is passed through thePN junction to inject carriers into the active region. Recombination ofthe injected carriers from the conduction band to the valence band inthe quantum wells results in photons that begin to travel in the lasercavity defined by the mirrors. The mirrors reflect the photons back andforth. When the bias current is sufficient to produce a populationinversion between the quantum well states at the wavelength supported bythe cavity, optical gain is produced in the quantum wells. When theoptical gain is equal to the cavity loss, laser oscillation occurs andthe laser is said to be at threshold bias and the VCSEL begins to ‘lase’as the optically coherent photons are emitted from the top of the VCSEL.

U.S. Pat. No. 8,774,246 describes light emitting devices with a currentblocking region formed using a depleted semiconductor heterojunctioninterface. Using this type of heterojunction interface for blockingallows a conductive channel to be formed by applying location selectivespecific doping changes either to the blocking region, or to the centerconductive region itself. In this approach, doping is delivered via adiffusion mechanism.

Zou et al. (D. Zhou and L. J. Mawst, “High-Power Single-ModeAntiresonant Reflecting Optical Waveguide-TypeVertical-Cavity-Surface-Emitting Lasers,” IEEE Journal of QuantumElectronics, 58, no 12, 1599-1606 (2002)) describes light emittingdevices that use a heterojunction current blocking region and a centeretched conductive channel, but the subsequent regrowth used in thisdesign is not planarizing and does not form an index guiding opticalmode in the center channel of the device. Instead, antiresonant deviceswith larger, optical modes that can leak to the adjacent area areformed. While this may be useful for very large emitters or closelyplaced arrays, the design approach is not desirable for single highoptical output efficiency and high modulation bandwidth VCSELs.

In Chriovsky et al. (L. M. F. Chriovsky, W. S. Hobson, R. E. Leibenguth,S. P. Hui, J. Lopata, G. J. Zydzik, G. Giaretta, K. W. Goossen, J. D.Wynn, A. V. Krishnamoorthy, B. J. Tseng, J. M. Vandenberg, L. A.D'Asaro, “Implant-Apertured and Index-GuidedVertical-Cavity-Surface-Emitting Lasers (I²-VCSELs),” IEEE PhotonicsTechnology Letters, 11, no 5, 500-502 (1999)) the current blockingregion is formed by ion implantation damage, and not through use of alow doped hetero-junction. The index guided optical mode is formed viaan etched mesa as in U.S. Pat. No. 8,774,246.

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one example technology where some embodiments describedherein may be practiced.

SUMMARY

In one embodiment, an etched planarized vertical cavity surface emittinglaser (VCSEL) can include: an active region; a blocking region over theactive region, the blocking region defining one or more aperturestherein; and one or more conductive channel cores in the one or moreapertures of the blocking region, wherein the one or more conductivechannel cores and blocking region form an isolation region. In oneaspect, the VCSEL can include a bottom mirror region below the activeregion, and a top mirror region above the isolation region. In oneaspect, the blocking region has a thickness from 1 nm to 500 nm. In oneaspect, the conductive channel core has a diameter of about 1 micron toabout 10 microns. In one aspect, the VCSEL includes a plurality of theconductive channel cores in the blocking region. In one aspect, theconductive channel core has higher refractive index than the blockingregion. In one aspect, the VCSEL is devoid of one or more of: an oxideaperture; oxidation; a mesa. In one aspect, the VCSEL can include aconductive wing layer integrated or in contact with tops of the one ormore conductive channel cores. In one aspect, the one or more conducivechannel cores are planarized. In one aspect, the one or more conducivechannel cores and mirror layers of the top mirror region are planarized.

In one embodiment, a method of making a VCSEL having a blocking regionwith one or more conductive channel cores in the blocking region isprovided. Such a method of making an embodiment of the VCSEL caninclude: forming the active region over a substrate; forming theblocking region over the active region; etching the one or moreapertures in the blocking region; and forming the one or more conductivechannel cores in the one or more apertures of the blocking region. Inone aspect, the method can include: coating a top of the blocking regionwith a chemical agent that inhibits etching while leaving one or moreregions without the chemical agent; and etching the one or more of theapertures in the blocking region in the one or more regions without thechemical agent. In one aspect, the method can include filling the one ormore of the apertures in the blocking region with the one or moreconductive channel cores by MOCVD. In one aspect, the method can includeremoving the chemical agent that inhibits the etching after the etchingto form the one or more apertures and before the filling of the one ormore apertures with the one or more conductive channel cores. In oneaspect, the method can include forming the conductive channel core toextend through the blocking region and contact the active region orcontact a top spacer region that is above the active region. In oneaspect, the method can include forming a plurality of the conductivechannel cores in the common blocking region. In one aspect, the methodcan include forming a conductive wing layer so as to be integrated or incontact with tops of the one or more conductive channel cores. In oneaspect, the method can include planarizing a top surface of the one ormore conducive channel cores.

In one aspect, the an etched planarized vertical cavity surface emittinglaser (VCSEL) can include: an active region; a conductive region overthe active region, the conductive region defining one or more aperturestherein; and one or more blocking cores in the one or more apertures ofthe conductive region, wherein the one or more blocking cores andconductive region form an isolation region. Accordingly, all of theteachings and embodiments of a VCSEL having a blocking region withconductive channel cores therein may be reversed so that the conductiveregion has blocking cores therein. As such, the features describedherein may be switched so that the embodiment of the VCSEL with theconductive region having blocking cores therein is provided.

In one embodiment, a method of making the VCSEL having the conductiveregion has blocking cores there is provided. Such a method can include:forming the active region over a substrate; forming the conductiveregion over the active region; etching the one or more apertures in theconductive region; and forming the one or more blocking cores in the oneor more apertures of the conductive region. Accordingly, all of theteachings and embodiments of making a VCSEL having a blocking regionwith conductive channel cores therein may be reversed so that the methodproduces a conductive region that has blocking cores therein. As such,the features of the methods described herein may be switched so that theembodiment of the VCSEL with the conductive region having blocking corestherein is made.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and following information as well as other features ofthis disclosure will become more fully apparent from the followingdescription and appended claims, taken in conjunction with theaccompanying drawings. Understanding that these drawings depict onlyseveral embodiments in accordance with the disclosure and are,therefore, not to be considered limiting of its scope, the disclosurewill be described with additional specificity and detail through use ofthe accompanying drawings.

FIG. 1 is a schematic of an embodiment of a VCSEL operating environment.

FIG. 2 is a schematic of an embodiment of a VCSEL layered semiconductoroperating environment.

FIG. 2A shows a top view with a squared cross-section of an isolationregion.

FIG. 2B shows a top view with a circular cross-section of an isolationregion with etching to form a mesa.

FIG. 3 is a diagram of first growth showing N-type DBR mirrors, activeregion with QWs capped with a blocking region.

FIG. 4 is a diagram showing an etched opening in the blocking region.

FIG. 5 is a diagram showing planarizing regrowth that forms an indexguiding, conductive channel.

FIG. 5A is a diagram showing planarizing regrowth that forms an indexguiding, conductive channel topped with a planar wings layer that coversthe blocking region.

FIG. 6 is a diagram showing planarizing regrowth that forms the indexguiding, conductive channel topped with a planar wings layer that coversthe blocking region and a P-type DBR mirror over the planar wings layer.

FIG. 6A is a diagram showing planarizing regrowth that forms the indexguiding, conductive channel (without the planar wings layer) and aP-type DBR mirror over the planar wings layer.

FIG. 7 is a diagram showing a plurality of conductive channel cores in acommon blocking layer.

FIG. 7A is a diagram showing a plurality of conductive channel coreshaving complex shapes in a common blocking layer.

FIG. 8 is a cross-sectional side view of in isolation region having ablocking region with a plurality of conductive channel cores therein.

FIG. 8A is a cross-sectional side view of in isolation region having ablocking region with a plurality of conductive channel cores therein andthe planarized wing layer over the plurality of conductive channel coresand blocking region.

FIG. 9 is a flow diagram of an embodiment of a method of manufacturing aVCSEL.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof In the drawings, similarsymbols typically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein.

Generally, the present advancement in VCSEL technology relates to ablocking region and conducting region formed by etching a central regionof the blocking region and depositing a conducting region therein. Theconducting region can include a material that is more electricallyconducting than the material of the blocking region during operation ofthe VCSEL and light emission in an active region. Accordingly, theblocking region and conducting region can form a heterojunction forselective current guidance. The conducting region can form a conductingchannel through the blocking region. The conducting region may beplanarized by forming a portion of the conducting region over theblocking region. Planarized layers, such as mirror layers, can be formedover the conducting region. Otherwise, the VCSEL can be prepared asstandard in the industry or as in the incorporated references ordescribed herein.

The semiconductor devices of the present invention can be manufacturedfrom any type of semiconductor. Examples of suitable materials includeIII-V semiconductor materials (e.g., prepared from one or more Group IIImaterial (boron (B), aluminium (Al), gallium (Ga), indium (In), thallium(Tl), and ununtrium (Uut)) and one or more Group V materials (nitrogen(N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) andununpentium (Uup) (unconfirmed))) and optionally some type IV materials.

The semiconductor device can include an active region having one or morequantum wells and one or more quantum well barriers. The quantum wellsand quantum well barriers can be separated by one or more transitionallayers therebetween. The transitional layers may also be referred to asinterfacial layers as they are located at the interface between thequantum wells and quantum well barriers. However, the active region canbe configured as any known or developed in the art of VCSELs.

Optionally, electrical confining layers can sandwich the active regionand provide optical gain efficiency by confining carriers to the activeregion. The confining layers can have a region of high energy band gapwhich in many III-V compounds translates to high aluminum content (e.g.,70%-100% Al for the type III material). The aluminum content can beselected to give the material a relatively wide band gap, as compared tothe band gap in the quantum well barriers of the active region. The wideband gap material can give the confining layer good carrier confinementand can increase the efficiency in the active region. In an exemplaryembodiment, the high aluminum region may also include an increase indoping. The confining layer can be doped with a p-type or n-type dopantdepending on whether the confinement barrier is on the n-side or p-sideof the active region.

The heterojunction conductive channel configuration can provide improvedfiber optic transceiver reliability, electro-optical bandwidth, and linkdistances by allowing implementation of small aperture (e.g., 2-6 μm)VCSEL devices. In high power VCSELs, the heterojunction conductivechannel configuration allows higher maximum power per VCSEL, and moreemitters per unit area in dense arrays.

This heterojunction conductive channel configuration enables moreefficient mass production of guided mode VCSELs by allowing use of oneor more MOCVD (metalorganic chemical vapor deposition) crystal growthsteps in fabrication. As such, the process can omit lateral steamoxidization, or formation of any oxide aperture.

FIG. 1 shows a planar, current-guided, VCSEL 100 having periodic layerpairs for top (124) and bottom (116) mirrors. A substrate 114 is formedon a bottom contact 112 and is doped with a first type of impurities(i.e., p-type or n-type dopant). A bottom mirror stack 116 is formed onsubstrate 114 and an optional bottom confining layer 118 is formed onthe bottom mirror stack 116. An active region 122 is formed over thebottom mirror stack 116, or over the bottom confining layer 118 (whenpresent). An optional top confining layer 120 is formed over the activeregion 122. In one optional aspect, the bottom confining layer 118 and atop confining layer 120 sandwich the active region 122. An isolationregion 128 is formed over the active region 112 or over the optional topconfining layer 120. The isolation region includes a lateral regionblocking region 127 and a central conducting channel core 129. Thebottom confining layer 118 and/or top confining layer 120 may be aspacer region between the active region and isolation region.Alternatively, the bottom confining layer 118 and/or top confining layer120 may be a conducting region. Thus, any spacer region bounding theactive region may be a confining region, conducting region, orsemiconductor spacer that is not confining or conducting.

An upper mirror stack 124 is formed over the isolation region 128. Ametal layer 126 forms a contact on a portion of stack 124. However,other VCSEL configurations may also be utilized, and various other VCSELlayers or types of layers can be used.

An isolation region 128 restricts the area of the current flow 130through the active region 122. Isolation region 128 can be formed by toinclude the lateral region blocking region 127 and a central conductingchannel core 129 by depositing the blocking region 127, forming anaperture therein that is then filled with the central conducting channelcore 129. The isolation region 128 can include a single layer blockingregion 127 or multiple layers of blocking layers, and/or a single layercentral conducting channel core 129 or multiple layers of centralconducting channel core layers.

Mirror stacks 116 (bottom) and 124 (top) can be distributed Braggreflector (DBR) stacks, and include periodic layers (e.g., 132 and 134,but may be switched from what is shown). Periodic layers 132 and 134 aretypically AlGaAs and AlAs, respectively, but can be made from otherIII-V semiconductor materials. Mirror stacks 116 and 124 can be doped orundoped and the doping can be n-type or p-type depending on theparticular VCSEL design. However, other types of VCSEL mirrors may beused.

Metal contact layers 112 and 126 can be ohmic contacts that allowappropriate electrical biasing of VCSEL 100. When VCSEL 100 is forwardbiased with a voltage on contact 126 different than the one on contact112, active region 122 emits light 136, which passes through top mirrorstack 124. Those skilled in the art will recognize that otherconfigurations of contacts can be used to generate a voltage acrossactive region 122 and generate light 136.

FIG. 2 illustrates the active region 122 and confining layers 118 and120 under isolation region 128 having the blocking region 127 andcentral conducting channel core 129. The blocking region 127 forms theouter current blocking regions 160, and the central conducting channelcore 129 forms the central mode confinement region 162. Active region122 is formed from one or more quantum wells 138 that are separated byquantum well barriers 140, where the transition layers may be the linesbetween the quantum wells 138 and barriers 140. The confining layers 118and 120 may optionally include high aluminum content regions 142 and144, respectively. The high aluminum content regions provide goodcarrier confinement in active region 122.

Confining region 120 can include a ramp region 146 that is positionedbetween active region 122 and high aluminum content region 144. Asdiscussed below, the combination of high aluminum content region 144 andthe ramp region 146 provide an injection structure with good carrierconfinement and good electron injection.

Depending on the design of the VCSEL device and the thickness of highaluminum content regions 142 and 144, the confining regions 118 and 120can optionally include spacer layers 148 and 150, respectively. Thethickness of spacer layers 148 and 150 can be dependent upon the kind ofVCSEL device being fabricated. In a vertical cavity resonant device suchas a VCSEL, or VCSEL the spacer layers provide resonant spacing betweenmirrors and provide that the quantum wells of the active region arecentered on a peak of the optical field if desired.

The confining layers 118 and 120 and active region 122 can be formedfrom one or more types of semiconductor materials, such as GaAs, AlAs,InP, AlGaAs, InGaAs, InAlAs, InGaP, AlGaAsP, AlGaInP, InGaAsP, InAlGaAs,SiGe, or the like.

In one example, the lower electrical confining layer is AlInP. Inanother example, the upper electrical confining layer can be AlInGaP.

FIG. 2A shows a top view with a squared cross-section of an isolationregion 128. FIG. 2B shows a top view with a circular cross-section of anisolation region 128 with etching to form a mesa. A single chip may havea plurality of the isolations regions 128 either planar as in FIG. 2A oretched to have a plurality of mesas as in FIG. 2B on a single chip.

The VCSEL heterojunction conductive channel configuration can be formedto include a heterojunction current blocking region, with a conductivechannel formed by etching an aperture in the blocking region, and ahigher refractive index conductive channel core being deposited in theetched aperture. The blocking region can be a lower refractive indexperimeter. The refractive index of the blocking region being lower canbe comparative to the higher refractive index of the conductive channelcore. This allows formation of guided optical modes. Now with theheterojunction conductive channel configuration, a VCSEL or VCSEL arraycan be more readily fabricated using standard MOCVD technology and otherstandard fabrication techniques that are currently employed in highvolume VCSEL manufacturing.

In one embodiment, a method of manufacture of the VCSEL with theheterojunction conductive channel configuration can include forming amirror region 116, forming an active region 122 over the mirror region116, and forming a blocking region 127 over the active region 122 asshown in FIG. 3. The formations can be by MOCVD. In one example, thestructure can include an undoped blocking layer 127 (e.g., InGaP, suchas In_(0.48)Ga_(0.52)P), which is lattice matched to GaAs and AlGaAs, asshown in FIG. 3. The blocking layer 127 is not subject to aggressiveoxidation in air that interferes with MOCVD based re-growth. Thus, theuse of MOCVD can be beneficial for forming the heterojunction conductivechannel configuration.

The blocking layer 127 can a center region selectively removed by wetchemical etch to transition from the structure of FIG. 3 to thestructure of FIG. 4. After etching the aperture 410 in the blockingregion (which aperture 410 is a recess with the active region 122 or topconfining region 120 as its base with the blocking region 127 as theside walls extending from the base), a conductive channel core 129 isformed in the etched aperture 410 by planarizing regrowth as shown inFIG. 5, such as by using a higher index of refraction material (comparedto the blocking region), such as Al_(0.15)Ga_(0.85)As. The planarizingregrowth is performed to fill the etched aperture 410 with theconductive channel core 120, and then to form any optional regions(e.g., conductive plane with wings 129 a) as shown in FIG. 5A, andmirror regions 124 over the etched region, as shown in FIG. 6. Theplanarizing regrowth is implemented by selection of MOCVD growthparameters to obtain higher attainable growth rates inside the aperture410. A selective area regrowth, followed by a top P-doped mirror (e.g.,distributed Bragg reflector—DBR) growth can also be used in to achieveplanarization. When the bottom mirror is P-doped the top mirror can beN-doped and the other layers of the VCSEL correspondingly formulated.

Accordingly, FIG. 3 shows the first growth of a DBR mirror 116, activeregion 122, and blocking region 127. FIG. 4 shows the etched aperture410 in the blocking region 127. FIG. 5 shows a planarizing regrowth thatforms the index guiding, conductive channel core 129. FIG. 5A showsplanarizing regrowth that forms index guiding conductive channel with aconductive plane with wings 129 a over the conductive channel core 129.FIG. 6 shows the planarizing layers of the top mirror 124. FIG. 6A showsan option where there is no conductive plane with wings 129 a over theconductive channel core 129, and instead the top mirror 124 is directlyover the conductive channel core 129 and lateral blocking region 127.

In one embodiment, the present VCSEL can be configured to include acenter conductive channel formed by etching the blocking region away,and having the etched region filled with a conducting region and thenhaving a subsequent series of planarizing layers deposited on top of theblocking region and conducting region to form an index guided opticalmode.

In one embodiment, the embodiments and processing can be reversed sothat the conductive layer is applied instead of the blocking layer, andthen the conductive layer is etched for form a cavity that is thenfilled with the blocking layer so as to form a blocking core. However,the blocking core would not have a blocking plane with wings in thisembodiment.

In one embodiment, a single substrate can include a plurality of VCSELemitters, which can be formed into an array. A macro substrate with amacro blocking region can be selectively etched and refilled withconducting channel cores in a number of locations to form the array ofVCSELs. Each conducting channel core can be an individual light emittingdevice that use a heterojunction current blocking region and a centeretched conductive channel, and the entirety of the conducting channelsand blocking regions can receive subsequent regrowth thereof withplanarizing layers. FIG. 7 shows such a laser array of VCSEL emitters ona single substrate. Each VCSEL emitter can include a conductive channelcore 129, where all VCSEL emitters are each surrounded by a commonblocking layer 127. FIG. 7B shows that the etching can be done to resultin conductive channel cores 129 having complex shapes, which can beaccomplished by selective deposition of a protectant that leaves complexshapes unprotected that are then etched into complex etched shapes.

The present configuration can result in a VCSEL devoid of an oxideaperture because the processing does not use lateral oxidation that candamage the semiconductor layers. The use of the blocking layer withconductive channel core uses semiconductor material with better thermalconnectivity. The thermal conductivity is better because of aluminumarsenide layers in the top mirror, and processing does not oxidize them.The bottom mirror can use binary materials. The reliability of the VCSELcan also be increased because the manufacturing method does not includecutting a trench near the active region and oxidizing into thesemiconductor.

Reliability of the VCSEL can be improved when the device operates atlower temperatures. In the current state of the art, the oxide confinedVCSEL heats more because of the low thermal conductivity of the oxidelayer. Trenches are cut in the device to allow the oxide layer to form.As such, the VCSELs provided herein can be devoid of such an oxide layerand/or trenches that allow oxide layers to form.

Most of the problems with laser device reliability are related to somekind of chemical process being set in motion at the tip of thatoxidation layer. Some reliability problems occur at the oxide tipbecause of the stress induced by the oxide layer. Most reliabilityproblems are exacerbated at high temperatures. The oxide confined lasershave reliability problems as a result of physical interaction withoxidation layer, were stress at the oxidation layer drives defects toform in semiconductor layers. In view thereof, it is expected that thelasers described herein should have less defects and less defectformation even at higher temperatures by lacking the oxide layers. Thepresent implant VCSELS can have improved reliability by not having theoxide layer.

Now with the present technology, very small apertures can be formed in ablocking layer to form one or more laser devices with improvedreliability. The very small aperture laser devices can now be very closeto each other. For example, the individual conductive channel cores canhave diameter (or other cross-dimensions) of from 1 micron to 10microns, from 1.5 microns to 5 microns, from 2 microns to 4 micros, orabout 2.5-3 microns. The individual conductive channel cores can beseparated by distances (e.g., minimum distance apart) from 1 micron to10 microns, from 1.5 microns to 5 microns, from 2 microns to 4 micros,or about 2.5-3 microns. This can include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,or more lasers on a common chip, where one or more (e.g., 4 or 5) can becoupled into a common optical fiber.

Common to chemical etching, a mask can be used to define the etchingpart and non-etching part. A mask or other chemical blocking materialcan be placed on the blocking layer with apertures defining where thechemical etch will occur. In one example, MOCVD deposition is used toform the conductive channel core. In one example, the non-etching regionis defined by a placing a layer of SiO₂ everywhere on the blocking layerexcept for leaving the one or more holes (circular or other shape) thatis the aperture. Then the SiO₂ is removed. After removing the SiO₂ thenMOCVD fills the holes with the higher refractive index material to formthe conductive channel cores. Then the conductive channel core isflattened out by adding more higher refractive index material to formthe layer with wings. The mirror can then be formed over the isolatingregion.

In one embodiment, the temperature of the MOCVD process can be modulatedwhile filling the aperture during the regrown can result in morematerial growing in the hole and then it planerizes later. Thetemperature of the regrowth process can determine how much planarizationoccurs.

In one aspect, the manufacturing process omits etching or otherwiseforming a mesa. Accordingly, the laser device does not include a raisedarea in the center of where the laser will be.

In one embodiment, the blocking region is InGaP. And that material, its48% I, 52% Ga, along with P. This InGaP material is lattice matched toGaAs.

The selective etching allows formation of various shaped apertures thatcan then be filled into shaped conductive channel cores 129 as shown inFIG. 7A.

FIG. 8 shows a cross sectional side view of a semiconductor having ablocking 127 region with a plurality of apertures filled with theconductive channel cores 129.

FIG. 8A shows a cross sectional side view of a semiconductor having ablocking region 127 with a plurality of apertures filled with theconductive channel cores 129, and a unitary conductive wing layer 129 aintegrated with or located on top of and contacting a plurality or allof the conductive channel cores 129.

FIG. 9 is a flow diagram of another process 900 of an embodiment of amethod of manufacturing a VCSEL as described herein. The process canincludes growing a first mirror region having a plurality of firstmirror layers having one or more indices of refraction (block 910) andthen (optionally) growing a first spacer region over the first mirrorregion (block 920). Then an active region is grown over the first spacerregion (block 930) (or over first mirror when first spacer region notgrown). Then an optional second spacer region is grown over the activeregion (block 935). Then a blocking region is grown over the secondspacer region (block 940) (or active region when second spacer regionnot grown). Then etching one or more apertures in the blocking region(only the blocking region is etched, the active region is not etched,optionally some or all of the second blocking region can be etched)(block 945). Then the one or more apertures are filled with a highrefractive index material (e.g., higher RI than blocking layer) (block950) to form the conductive channel core. The process 900 can alsoinclude planarizing the conductive channel core, such as by forming thewings (block 960), and then growing a second mirror region having aplurality of second mirror layers having one or more indices ofrefraction (block 970).

Also, the active region or whole semiconductor layers of a VCSEL can beproduced with molecular beam epitaxy (MBE). Lower growth temperaturesduring the MBE can be used to prepare the VCSEL semiconductor layers.The growth of these structures by MBE can be performed at < (less than)500° C. Comparatively, the temperatures for MOCVD can be > (greaterthan) 600° C. Additionally, the VCSELs can be prepared by methods thatare similar to MBE, such as GSMBE (gas source MBE) and MOMBE(metalorganic MBE) or the like that can produce the regions asdescribed.

The chemical etching can be any that is useful and known in the art.

In one embodiment, the orientation of the blocking region and conductiveregion can be swapped, such that the blocking region is the coresurrounded by the conductive region. Here, the conductive regionincludes an aperture having the blocking core.

In one embodiment, the lack of trenches and oxidation can result in theconductive cores (or central blocking region) being closer together thanprior devices. Prior devices, due to trenches and oxidation, can havethe cores (conductive or blocking) at about 21 to 25 microns apart, inan example. However, because the current device omits the trenches andoxidation, the cores (conductive or blocking) can be must closertogether, such as 4 microns, or from 2-6 microns, of from 1-8 micronsapart (center to center)

Now, with cores center to center at about 4 microns, for example, highdensity arrays can be achieved. The high density can allow for coherentarrays with cores with the same phase. Also, there can be some controlof coherence of beams in a phased array, which can focus down to smallspot for use in scanning. Additionally, more precise control of the highdensity array allows for laser weaponry to use the high density arraysachieved with the present technology.

The technology can allow coherent arrays, which means that all of thecores have the same phase or that you can control the phase between thecores, which can provide a laser beam that can be pointed to a desiredlocation without physically turning the laser. In an example, a fighterplane there is a phased array in the nose that illuminates anotherfighter plane, and thereby the phased array can point anywhere. Controlof the coherence of the beam of a phased array can allow for focus ofthe beam down to a small spot. Such control allows for the invention tobe used in scanning applications. The control may also be useful in alaser weapon because the arrangement can distribute many of the coresover a large area, which can control the heat dissipation, and controlof the phase of all of the cores can allow them to be combined, such asby focusing, so that all of the cores work together to combine theirpower to get a very large amount of power per unit area when focused.

In one embodiment, an etched planarized vertical cavity surface emittinglaser (VCSEL) can include: an active region; a blocking region over theactive region, the blocking region defining one or more aperturestherein; and one or more conductive channel cores in the one or moreapertures of the blocking region, wherein the one or more conductivechannel cores and blocking region form an isolation region. In oneaspect, the VCSEL can include a bottom mirror region below the activeregion, and a top mirror region above the isolation region. In oneaspect, the VCSEL can include a bottom spacer region between the bottommirror region and active region, and a top spacer region between theactive region and blocking region. In one aspect, the conductive channelcore extends through the blocking region and contacts the active region.In one aspect, the conductive channel core extending through theblocking region and contacts the top spacer region. In one aspect, theblocking region has a thickness from 1 nm to 500 nm, from 1 nm to 30 nm,from 1 nm to 10 nm, or from 1 nm to 3 nm. In one aspect, the conductivechannel core has a thickness the same as the blocking region. In oneaspect, the conductive channel core has a diameter of about 1 micron toabout 10 microns. In one aspect, the conductive channel core has adiameter of about 2 micron to about 6 microns. In one aspect, theblocking region or blocking layer is InGaP. In one aspect, theconductive channel core is AlGaAs. In one aspect, the one or moreconducive channel cores are planarized. In one aspect, the one or moreconducive channel cores and top mirror are planarized.

In one embodiment, the VCSEL can include a plurality of the conductivechannel cores in a common blocking region. In one aspect, the VCSEL caninclude up to five of the conductive channel cores in a common blockingregion, or more than five.

In one embodiment, the conductive channel core has higher refractiveindex than the blocking region. In one aspect, the blocking region has alower refractive index than the conductive channel core. In one aspect,the conductive channel core has a refractive index from about 3.7 to 3.In one aspect, the blocking region has a refractive index from about 3.7to 3.

In one embodiment, an array of VCSELs can include a plurality of theindividual VCSELs described herein in accordance with any embodiment.

In one embodiment, the VCSEL can exclude certain features common inVCSELS. In one aspect, the VCSEL is devoid of an oxide aperture. In oneaspect, the VCSEL is devoid of oxidation. In one aspect, the VCSEL isdevoid of a mesa.

In one embodiment, the VCSEL can include a conductive wing layer. In oneaspect, the conductive wing layer is integrated with tops of the one ormore conductive channel cores. In one aspect, the conductive wing layeris separate and in contact with tops of the one or more conductivechannel cores.

In one embodiment, a method of making the VCSEL can include: forming theVCSEL having the active region; blocking region over the active region,the blocking region defining the one or more apertures therein; and theone or more conductive channel cores in the one or more apertures of theblocking region. In one aspect, the method can include forming theblocking region. In one aspect, the method can include forming theblocking region, and etching one or more of the apertures in theblocking region. In one aspect, the method can include: forming theblocking region; coating the top of the blocking region with a chemicalagent that inhibits etching while leaving one or more regions withoutthe chemical agent; and etching one or more of the apertures in theblocking region in the one or more regions without the chemical agent.In one aspect, the method can include: forming the blocking region;coating the top of the blocking region with a chemical agent thatinhibits etching while leaving one or more regions without the chemicalagent; etching one or more of the apertures in the blocking region inthe one or more regions without the chemical agent; and filling the oneor more of the apertures in the blocking region with the one or moreconductive channel cores.

In one aspect, the method can include removing the chemical agent thatinhibits the etching after the etching to form the apertures and beforethe filling of the aperture with the one or more conductive channelcores. In one aspect, the method can include removing the chemical agentthat inhibits the etching after the filling of the aperture with the oneor more conductive channel cores.

In one embodiment, the method can include forming the bottom mirrorregion below the active region, and forming the top mirror region abovethe active region, blocking region, and conductive channel core. In oneaspect, the method can include forming the bottom spacer region betweenthe bottom mirror region and active region, and forming the top spacerregion between the active region and isolation region.

In one embodiment, the method can include forming the conductive channelcore to extend through the blocking region and contact the activeregion. In one aspect, the method can include forming the conductivechannel core to extend through the blocking region and contact the topspacer region. In one aspect, the method can include forming theplurality of the conductive channel cores in the common blocking region.In one aspect, the method can include forming the conductive channelcore to have the higher refractive index than the blocking region. Inone aspect, the method can include forming the blocking region have alower refractive index than the conductive channel core.

In one embodiment, the method can include using MOCVD to form the one ormore conductive channel cores. In one aspect, the method can includeusing MOCVD to form the one or more conductive channel cores, and formconductive plane with wings layer over the one or more conducive channelcores. In one embodiment, the method can include using MOCVD to form theone or more conductive channel cores, form conductive plane with wingslayer over the one or more conducive channel cores, and form the topmirror over the one or more conducive plane with wings layer.

In one embodiment, various layers can be planarized. In one aspect, themethod can include planarizing the top mirror. In one aspect, the methodcan include forming the one or more conducive channel cores to beplanarized. In one aspect, the method can include forming the one ormore conducive channel cores and top mirror to be planarized.

In one embodiment, the method can include forming an array of theVCSELs.

In one embodiment, the method can include forming the conductive winglayer integrated with tops of the one or more conductive channel cores.In one aspect, the method can include forming the conductive wing layerseparate and in contact with tops of the one or more conductive channelcores.

In one embodiment, an etched planarized vertical cavity surface emittinglaser (VCSEL) can include: an active region; a conductive channel regionover the active region, the conductive channel region defining one ormore apertures therein; and one or more blocking cores in the one ormore apertures of the conductive channel region, wherein the one or moreblocking cores and conductive channel regions form an isolation region.Accordingly, the elements recited herein may be applied to such a VCSELthat has the blocking member as a blocking core instead of theconductive member being the conducive core. Modifications in accordancewith this embodiment are included herein. The methods of manufacturingmay also be modulated so that the blocking member as a blocking coreinstead of the conductive member being the conducive core

One skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the essence of the disclosedembodiments.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, agroup having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells,and so forth.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

All references recited herein are incorporated herein by specificreference in their entirety.

The invention claimed is:
 1. An etched planarized vertical cavitysurface emitting laser (VCSEL) array comprising: an active region; ablocking region over the active region, the blocking region defining aplurality of apertures therein, wherein the plurality of apertures arelaterally arranged in the blocking region; a plurality of conductivechannel cores in the plurality of apertures of the blocking region,wherein the plurality of conductive channel cores and blocking regionform an isolation region; a bottom mirror region below the active regionand the plurality of conductive channel cores; a top mirror region abovethe isolation region and the plurality of conductive channel cores; anda top light emitting surface for the plurality of conductive channelcores; wherein the plurality of conducive channel cores, mirror layersof the top mirror region, and light emitting surface are planarized, andwherein the VCSEL array is devoid of a mesa.
 2. The VCSEL of claim 1,wherein the blocking region has a thickness from 1 nm to 500 nm.
 3. TheVCSEL of claim 1, wherein each conductive channel core has a diameter ofabout 1 micron to about 10 microns.
 4. The VCSEL of claim 1, whereineach conductive channel core has higher refractive index than theblocking region.
 5. The VCSEL of claim 1, wherein the VCSEL is devoidof: an oxide aperture; and oxidation.
 6. The VCSEL of claim 1, furthercomprising a conductive wing layer integrated or in contact with tops ofthe plurality conductive channel cores.
 7. A method of making the VCSELof claim 1, comprising: forming the active region over a substrate;forming the blocking region over the active region; etching theplurality of apertures in the blocking region; and forming the pluralityof conductive channel cores in the plurality of apertures of theblocking region.
 8. The method of claim 7, further comprising: coating atop of the blocking region with a chemical agent that inhibits etchingwhile leaving a plurality of without the chemical agent; and etching theplurality of the apertures in the blocking region in the plurality ofregions without the chemical agent.
 9. The method of claim 8, furthercomprising filling the one or more of the apertures in the blockingregion with the plurality of conductive channel cores by MOCVD.
 10. Themethod of claim 8, further comprising: removing the chemical agent thatinhibits the etching after the etching to form the plurality ofapertures and before the filling of the plurality of apertures with theplurality of conductive channel cores.
 11. The method of claim 7,further comprising forming the conductive channel core to extend throughthe blocking region and contact the active region or contact a topspacer region that is above the active region.
 12. The method of claim7, further comprising forming a plurality of the conductive channelcores in the common blocking region.
 13. The method of claim 7, furthercomprising forming a conductive wing layer so as to be integrated or incontact with tops of the plurality of conductive channel cores.
 14. Themethod of claim 7, further comprising planarizing a top surface of theplurality of conducive channel cores.
 15. The VCSEL of claim 1, whereinthe conductive channel cores are separated from each other by about 1micron to 10 microns.
 16. The VCSEL of claim 15, wherein the blockingregion is InGaP and the conductive channel cores are AlGaAs.
 17. TheVCSEL of claim 6, wherein the conductive wing layer extends between andconnects the plurality of conductive channel cores.
 18. The VCSEL ofclaim 15, wherein each conductive channel core has a center point, and adistance between each center point is about 2 microns to about 6microns.
 19. An etched planarized vertical cavity surface emitting laser(VCSEL) array comprising: an active region; a conductive region over theactive region, the conductive region defining a plurality of aperturestherein; a plurality of blocking cores in the one or more apertures ofthe conductive region, wherein the plurality of blocking cores andconductive region form an isolation region; a bottom mirror region belowthe active region, the conductive region, and the plurality of blockingcores; a top mirror region above the isolation region, conductiveregion, and the plurality of blocking cores, and a top light emittingsurface for the conductive region; wherein the conductive region,plurality of blocking cores, mirror layers of the top mirror region, andlight emitting surface are planarized, and wherein the VCSEL array isdevoid of a mesa.
 20. A method of making the VCSEL of claim 19,comprising: forming the active region over a substrate; forming theconductive region over the active region; etching the plurality ofapertures in the conductive region; and forming the plurality ofblocking cores in the plurality of apertures of the conductive region.